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Re: Rebuilding the Central of Georgia #408

Posted: Tue Aug 18, 2015 5:19 pm
by John_S
Started on the throttle packing gland today. This is essentially a 1" NPT pipe plug that serves two purposes:

1) The throttle rod packing gland
2) A large inspection port/cleanout plug in the backhead.

Apparently you can no longer purchase solid brass 1" plugs anymore, only hollow. Because I need more material there for the packing gland, I bored out the hollow pipe plug and machined a 5/16" long disc and silver soldered it in.
408_155.jpg
1" NPT pipe plug and filler plug to go inside
I cut a small slot across the top and down one side of the filler piece so the solder would flow down and completely fill the small space on the inside, down between the two parts.
408_156.jpg
1" NPT pipe plug after brazing
Then, drilled the 1/4" hole for the throttle rod and the 1/2" bore for the packing nut, as well as the two 8-32 studs for the nut.
408_157.jpg
Half the packing gland done
Got started on the nut but had to quit early today. It's being made from a piece of 1.25" brass round stock. I should be able to finish that up tomorrow.

edit: forgot I snapped this with my phone ... wish it was in focus!
packingGlandGlow.jpg
1" fitting after brazing

Re: Rebuilding the Central of Georgia #408

Posted: Wed Aug 19, 2015 2:02 pm
by John_S
Finished up the throttle rod packing gland this morning.
408_158.jpg
Turning the nut
408_159.jpg
Finished with lathe operations on the nut
408_160.jpg
Nut drilled out for the 1/4" rod and two 8-32 studs.
And the finishing touch, shape it and cut the studs:
408_161.jpg
Packing gland done
Painted boiler, ready for the throttle to be installed ... and all the other stuff!
408_162.jpg
Almost ready to go back on the chassis
I'm waiting on a 1" NPT tap to open up the bushing on the backhead a bit so the plug/packing gland threads deeper into the boiler. Currently it leaves about 5/8" of threads on the outside. Need that to be one, maybe two, threads exposed so the packing gland is close to the backhead.

Re: Rebuilding the Central of Georgia #408

Posted: Fri Aug 21, 2015 6:20 pm
by John_S
My hernia surgery went well, but I'm out of commission for the next couple weeks. About all I'll be able to work on is drawing up and laying out the throttle lever, rod, and bell crank for the ball valve in steam dome.

Re: Rebuilding the Central of Georgia #408

Posted: Fri Aug 21, 2015 7:29 pm
by DFB
John,
I'm glad your surgery went well. I feel your pain. I had a Hydrocelectomy after a bad derailment at work last October. I've been following your rebuild of your locomotive and love seeing what your doing. Impressive!
Dale Berman

Re: Rebuilding the Central of Georgia #408

Posted: Sat Aug 22, 2015 8:44 pm
by steamin10
Sorry for your troubles. I can tell you to take it slow, as re-injury can have devastating results. Dont pick up anything heavier than a cup of coffee. Stay away from TV and get square eyes traveling the U-Tube stuff that interests you.

At one time, I returned to work after some groin surgery, and cost myself another 4 weeks on the bench. Dont try to be a hero, (he-man). Take your time and lower your risk.

Re: Rebuilding the Central of Georgia #408

Posted: Wed Sep 02, 2015 3:35 pm
by John_S
Recovery is going well, but I'm still on doctor's orders to take it easy. I did some light work starting on the ball valve for the throttle. Threw away the handle that came with it and made a new actuator that will connect to the throttle rod via a fabricated piece that I've not gotten to yet.

In the end this ball valve will be easily removable. There'll be a single cotter pin that connects the valve actuator and the rod linkage -- you can see the 3/16" pin with a hole in it for the cotter pin in the photo below. Once that's pulled out you can undo the rod and linkage and pull it completely out the backhead, then the ball valve simply unscrews from the elbow in the supply pipe.

Mocked up in place, waiting for the rest of the linkage to get made up. By the way, all these parts are 304SS.
408_163.jpg

Re: Rebuilding the Central of Georgia #408

Posted: Mon Sep 07, 2015 1:26 pm
by John_S
Fabricated the other half of the ball valve actuator this morning and got it brazed to the throttle rod.

The rod has a .875" offset bent into it so it aligns with the packing gland in the backhead. It may not be the prettiest part, but it works perfectly.
408_164.jpg
Ball valve actuator
408_165.jpg
Valve installed

Re: Rebuilding the Central of Georgia #408

Posted: Wed Sep 09, 2015 4:45 pm
by John_S
Little bits at a time now.

Finished getting the throttle valve and dry pipe installed, including packing the front gland. After we tap out the bushing on the backhead I can cut the throttle rod to length -- you can see it's way long in the photo below.

Re: Rebuilding the Central of Georgia #408

Posted: Sun Sep 13, 2015 5:35 pm
by John_S
Touchdown!
408_167.jpg
408_168.jpg
Back on the chassis!
A little tweaking to the ash pan is required as it's contacting the rear of the mudring. A few moments with the grinder and that'll be sorted.

Re: Rebuilding the Central of Georgia #408

Posted: Mon Sep 14, 2015 7:36 am
by makinsmoke
Nice job of fabricating.

I'm assuming you made the new handle with the hole/slot offset for the stem so that it closes when you push the rod forward. Ball valve handles are usually aligned so that when they are parallel to the valve body the valve is open. Yours just appears closed in your photo and pushing the rod forward would appear to open it. But as I say you must have cut the opening in your new valve so the ball sits properly aligned.

I don't see any swivel mechanism in your linkage. Are you expecting the rod to flex to allow for offset at the valve handle as you push it?

Also, did you slot the rod before brazing the extension?

Please don't take any of these questions as criticism. I really appreciate your hard work and talent, and am just trying to learn.

Take care,
Brian

Re: Rebuilding the Central of Georgia #408

Posted: Mon Sep 14, 2015 1:52 pm
by Pontiacguy1
a 1/4" diameter SS throttle rod that is probably 14 or 15" long at minimum will easily bend enough to go through a 1/4 turn sweep. It's the way that all of my throttle valves are set up and some of them have worked for years. I've seen some that were this way for 35+ years and there wasn't a problem with that part when they were torn down.

Re: Rebuilding the Central of Georgia #408

Posted: Mon Sep 14, 2015 6:10 pm
by John_S
makinsmoke wrote:I'm assuming you made the new handle with the hole/slot offset for the stem so that it closes when you push the rod forward. Ball valve handles are usually aligned so that when they are parallel to the valve body the valve is open. Yours just appears closed in your photo and pushing the rod forward would appear to open it. But as I say you must have cut the opening in your new valve so the ball sits properly aligned.
The slot in the new handle is at a different angle than the handle that comes with it. When the rod is in the forward position the valve is fully closed. Pulling the rod 90deg counter clockwise towards the backhead opens it fully.
makinsmoke wrote:I don't see any swivel mechanism in your linkage. Are you expecting the rod to flex to allow for offset at the valve handle as you push it?
A swivel is not necessary because the flex in the rod is minimal. Once the ball valve wears a bit it's probably non-existent. I made my mogul throttle valve exactly the same and it has worked perfectly so far with the exception of me adding a quadrant to it. Once it wore a bit it became loose enough that the boiler pressure could push the rod out the packing gland -- and opening the throttle!
makinsmoke wrote:Also, did you slot the rod before brazing the extension?
Yes, there's a 1/16" slot in the end of the rod.
makinsmoke wrote:Please don't take any of these questions as criticism. I really appreciate your hard work and talent, and am just trying to learn.
I don't mind at all! I share all this so people can see how I, personally, go about this madness and so folks can offer their own suggestions.